smoke coming from under engine cover!!!!!

[hondakillrsx]

hey all,
I've got a big problem. yesterday after spending the whole day fishing we returned to the marina, turned off the engine and after a minute I turned and saw smoke coming from under the engine cover! It smelled like electrical smoke (kinda) so I unplugged the battery and it did stop. after doing a quick inspection I wasn't able to find any toasted wires or anything like that. It doesn't seem to be an over heating issue either because we put the battery back on when we got home and sure enough it started again. The motor is a 93 two stoke Force 50. Please let me know if this has happened to any of you. I need my fishing!!

thanks,
Lane

 

[pnwboat]

Re: smoke coming from under engine cover!!!!!

Maybe the voltage regulator? Check you charging voltage. It should be a minimum of 13.5 volts at 2000 RPM. Hard to say if you can't pinpoint the exact source of the smoke.

 

[sentinel]

Re: smoke coming from under engine cover!!!!!

Not familiar with your engine but....... if a visual does not show melted insulation on wires, and no blistering or paint discoloration on any modules, then is is likely you are overheating coils of your charging circuit which is likely under the flywheel.

This could be caused by a shorted rectifier, a battery going bad, too much load current from external devices, or some other wiring short which causes the coils to supply too much current which will melt the winding insulations.

Pulling the flywheel takes skill and proper equipment to avoid further damage to the engine, but may be necessary to isolate the problem.

To ignore it will be a $$$ mistake. Good Luck. -Larry

 

[hondakillrsx]

Re: smoke coming from under engine cover!!!!!

thanks guys, i'll try and get some more info and see where it is coming straight from.

 

[hondakillrsx]

Re: smoke coming from under engine cover!!!!!

ok I took a look at it a couple minutes ago and found where it is coming from. Here are a couple of pictures, it is the little black box with several wires coming of it. two of them go up under the flywheel. anyone know what this is and if my motor is dead?

 

[Stachi]

Re: smoke coming from under engine cover!!!!!

Remove it , bring it to your local marine parts supply , and say " I need one that looks better than this one ".....lolol...it looks like it needs to be replaced in my opinion...lol

 

[CharlieB]

Re: smoke coming from under engine cover!!!!!

Too late!!!!

That is the rectifier, the smoked wire is one of the yellow AC wires from the stator.

Most probably the rectifier shorted across, feeding 12 volts DC back into the stator, toasting the charging coils on the stator.

I would bet you need BOTH. HOWEVER, since there is NO RETURN on electrical you should TEST EVERYTHING and PROVE the fault before ordering anything.

Disconnect the battery.

Disconnect all wires from the rectifier, save your picture so you will know which wire came from where.

Using an ohms meter test the red wire on the rectifier to the smoked terminal, now reverse your leads and retest. A good rectifier will read one direction only. Repeat both test on the other yellow terminal to the red terminal.

Now test the stator wires to each other, then each one to ground.

Neither should read to ground, you should have a low ohm's number testing the wires together.

Write down ALL the results of your tests and repost here, and/or compare to the chart found in the free outboard troubleshooting guide at CDI Electronics.com

 

[sentinel]

Re: smoke coming from under engine cover!!!!!

I would suggest one other test on the stator coils.....reason is the resistance(impedance) of normal stator coils "could" be rather low in resistance depending on the number of turns and the wire gauge of this engine.

A manual will tell you what nominal resistance should be....but meanwhile you can test the stator by seeing if you have an AC voltage (under 12 volts likely) on the wires coming out from under the flywheel when you pull start the motor with the plugs removed(to make it pull faster and easier).

Just a quick check to see if anything remains of the stator windings....... hopefully there are no shorted turns. -Larry

 

[hondakillrsx]

Re: smoke coming from under engine cover!!!!!

ok it will probably take me a couple days to get back out to do the tests. Because I don't know too much about outboard motors, can one of you give me a quick run down of what the stator and rectifier do so I can maybe get an idea of what happened?

thanks again for all your help.

 

[sentinel]

Re: smoke coming from under engine cover!!!!!

OK, in the rough....

Stator = Stationary coils. Flywheel magnet spins past it inducing a voltage into the coil windings. When the magnet continues past the windings, the induced voltage reverses. The net effect over this short time period is to cause an AC voltage to appear on the coil wires.

Because AC voltage cannot charge a battery, a solid state rectifier is used to "convert" the AC voltage to DC voltage which will charge the battery. AC voltage can by itself power lights etc., just like DC voltage can however.

Unless you have more wires attached to the same point as the wires from the stator, then your engine does not use raw AC voltage. Just DC.

Rectifiers can come in a variety of ways which I will not get into. It appears from the earlier comment that your rectifier is a simple half-wave rectifier which is ideal for charging a battery.

Anyone desiring to troubleshoot and repair their engine electronic circuits should read up on the fundamentals of basic AC/DC electricity and entry level electronics. Your local dealers (DEPEND) on your confusion or lack of knowledge for their livelyhood $$$. 'nuff said on that! -Larry

 

[hondakillrsx]

Re: smoke coming from under engine cover!!!!!

Ok guys,
I didnt write the numbers down because every time I would get a reading it would just max the needle out. So I didn't get any omh reading from any of the wires after they were taking off the rectifier. I did however max out when I tested the reading from the yellow to the other yellow.
I did the tests while they were still connected and EVERY wire would read while grounded, but like I stated before, after I took them off nothing.
Also I did take the spark plugs out and tried to get a reading for AC voltage and didn't even get a small spike.
From what you guys have said and my little knowledge of electronics I would have to say that both need to be replaced. What do you guys think?

 

[sentinel]

Re: smoke coming from under engine cover!!!!!

If you did the AC test carefully and it showed no AC voltage at all...then the charging coils under the flywheel or connecting wires to it are burned open. The rectifier should be replaced now (even if it is not shorted) because of its life expectancy after the wire heating problem.

This puts you back to what "caused" the short and the burned wires in the first place*.... and that is too difficult to determine without examining the motor wiring for intermittant shorts, the boats electrical circuit during operation, the cell condition of the battery, and the engine temperature which heats the rectifier by conduction. Any of these things can be the root problem besides the normal failure of a rectifier diode over time.

*e.g., a high electrical load (current) from too many boat things being powered when the battery or its condition cannot keep up with it. This causes the charging circuit to "TRY" and supply more power than it should....

Merely assuming a replacement of coils & rectifier will cure everything could cause this to be repeated at your $$expense$$ again....only a shop or technician with experience can isolate the underlying cause as to what actually happened here. Sorry.... -Larry